Proper maintenance of diesel engines is good for your rental company, good for your pocketbook and good for the environment - if you put safety first.

While most veteran professional mechanics are trained in safe working practices, service technicians new to the equipment rental field must often learn by doing. Therefore, mechanics new to the industry should be well-versed in the following basic safety precautions:

* Always ensure that the engine is properly supported and in safe condition before you attempt to use force to loosen any nuts, bolts or plugs. Wherever possible, initially slacken tight fastenings before raising the vehicle off the ground or removing the engine from its mountings.

* A vehicle should always have its gearbox in neutral; never start the engine unless the load has been removed and the hand brake applied.

* Never run catalytic converter-equipped engines without the exhaust system heat shields in place.

* Before starting work, allow oil, coolant or other fluids to cool to avoid scalding.

* Never siphon fuel, coolant, cooling agents, solvents or liquids by mouth or allow prolonged contact with skin.

* Take off watches, rings or other jewelry. Keep long hair and loose clothing well out of the way of any moving parts.

* Keep tools away from the top of the battery. They could cause a short circuit and possible explosion.

* Never lean over to work on a running engine.

* Never take risky shortcuts or rush to finish a job.

* Don't pour drained engine fluids down the drain. Don't mix used oil with other materials, such as paints and solvents. Take used oil to an oil-recycling bank.